BEREKEI, Russia - A handsome, new, white brick house, still lacking windows, sits deserted in the middle of this quiet agricultural village in Dagestan, the homeowner having slipped away midconstruction with his wife and three small children to join the Islamic State.

He was not the first. That came in January, soon after leaders of the long-running Islamist insurgency here in Dagestan, Russia's southernmost republic, began pledging allegiance to the self-proclaimed caliphate in Syria and Iraq. Around 30 men and women, townspeople say, have melted away this year.

"When they lived here they were all followers of one extremist line of Islam, so when one left, he became an example and the others left, too," said Capt. Abbas Karaev, 27, the village policeman, sitting in Berekei's squat municipal building, a structure so dilapidated and dusty it appeared abandoned. "They were told it was a jihad in Syria, and they would go to paradise if they died in this war."

Threat has 'diminished'

Much like the disaffected Muslim communities in Europe, the Caucasus region and the swath of former Soviet republics across Central Asia have become a vital recruiting ground for the Islamic State. Law enforcement officials estimate that there are at least 2,000 fighters from the Caucasus among up to 7,000 recruits from Russia and the former Soviet Union now in Syria and Iraq.

At the same time, the Islamic State is steadily establishing a foothold in the Caucasus. It is tapping into the rage and resentment over Russia's constant, brutal and arbitrary security presence in order to foster a new crop of homegrown, fanatical opponents to revive the insurgency that the Kremlin suppressed.

The majority Sunni population in the region has been further inflamed by the Russian military's intervention in Syria on the side of President Bashar Assad, a member of a Shiite sect who has killed tens of thousands of his Sunni opponents.

For the Kremlin, the ever more pronounced links between the Islamic State and the Caucasus provoke anxiety.

More than a decade ago, Russians were terrorized by a devastating series of attacks on schools, airplanes, a theater, the Moscow Metro and other public targets mostly at the hands of Chechens. The prospect of thousands of battle-hardened, Russia-hating jihadis returning under the banner of the Islamic State, or of a new group of native, fanatical fighters fanning out across Russia, is alarming.

Islamic State remains active in the Caucasus region, releasing a stream of sophisticated propaganda videos and promising to return to exact revenge for Russia's actions.

Certainly, President Vladimir Putin is concerned. When he announced in September that he would deploy the Russian air force in Syria, part of his stated rationale was to destroy the militants there before they could strike at home. Then just weeks later, on Oct. 31, a bomb exploded on a charter jet bringing mostly Russian vacationers back from Egypt, killing all 224 on board. The Islamic State claimed responsibility.

It is all a far cry from the early days of the Syrian civil war, when Russia welcomed the prospect of its most violent extremists lured away by the seductive buzz of jihad. "This sewer of people flowing from here to Syria means that the threat here has diminished," said Zubairu Zubairuev, a spokesman for the Dagestan government, who nevertheless denied that the government actively helped young radicals to leave or, as human rights advocates have said, killed those who stayed.

'Simple message'

Then in June came the declaration of the so-called Dagestan Governorate of the Islamic State and the start of an almost daily chorus of threats against Russia on social media.

A recruitment video made by a charismatic, young radical imam appeared on an Islamic State website in August.

Speaking in Russian, the imam, Kamil Sultanakhmedov, called on fellow Muslims to "join the mujahedeen of the Caucasus," while lauding the benefits of leaving Dagestan.

"Today, the Islamic State is making your jihad easier," said Sultanakhmedov, who had been the imam in the village of Novokayakent at a mosque frequented by Salafis, ultraconservative Islamists whose strict interpretation of religious texts has inspired extremism. "Today, you can fearlessly send your family, your parents, to a place where the infidels will never enter their house, never mock them or intimidate them."

He also threatened Russia, saying the Islamic State would eventually spread from Iraq and Syria to the Caucasus. "We will take this land away from you," he said. "We will kill you; we will slaughter you, burn you; and, if needed, we will make you sink. You will try on our orange robes and taste the heat of our swords."

Not all of the recruitment videos focus on fighting. Some discuss the orderly management of utilities and garbage collection in the Islamic State, for example, or highlight animal husbandry and beekeeping.

"They offer them some kind of feasible political project," said Ekaterina Sokirianskaia, who analyzes the Caucasus for the International Crisis Group. In contrast, federal law enforcement agents here have been sweeping up Muslims en masse from Salafi mosques and forcing them to submit repeated DNA samples.

In Makhachkala, the capital of Dagestan, a lawyer who defends Salafi clients said that the Islamic State has succeeded in Dagestan for three reasons: the simplicity of its message, the fact that it has a tangible achievement in seizing land in Iraq and Syria, and the much-publicized cruelty against its enemies.

"We are going to return soon and we are going to kill everyone - that is a simple message," said the lawyer.